Oil and gas wells are drilled into geological formations containing oil or natural gas. Some wells have a casing and a smaller production tubing within the casing. This provides two paths for gas to flow to the surface. Gas may flow upward in the space inside the casing and surrounding the tubing or gas may flow inside the tubing. Valves may be provided at the well head to control the flow of gas on each of these paths.
An oil or gas well can become loaded by liquids that accumulate in the well. these liquids can be pumped out of the well to facilitate the free flow of gas and/or oil out of the well.